Lisfranc injuries (tarsometatarsal complex)
Lisfranc injuries are disruptions of the tarsometatarsal (TMT) joint complex ranging from subtle ligamentous sprains to frank fracture-dislocations. They are important to recognise in the emergency department because missed or delayed diagnosis commonly leads to chronic midfoot pain, instability and post‑traumatic osteoarthritis (IMEG Fifth Report).
An organised approach below covers anatomy and mechanism, clinical clues, imaging strategy, ED priorities, triage/transfer decisions and definitive management principles.
Anatomy and biomechanics
The Lisfranc (TMT) complex stabilises the medial longitudinal and transverse arches. The key stabiliser is the Lisfranc ligament - a stout interosseous ligament running from the lateral surface of the medial cuneiform to the medial base of the second metatarsal. The base of the second metatarsal sits as a keystone between the cuneiforms; disruption here allows midfoot collapse and diastasis.
Typical mechanisms:
- Axial load on a plantarflexed foot (falls, road traffic collisions, pivoting sports).
- Direct crush injuries.
- Twisting injuries.
High‑energy trauma more often produces bony fractures; low‑energy mechanisms may produce purely ligamentous injury.
Clinical presentation and red flags
- Local signs: dorsomedial midfoot pain and swelling; focal TMT tenderness (classically between the first and second metatarsal bases). Plantar ecchymosis (midfoot bruising) is a characteristic and highly suggestive finding (IMEG).